Cold pilger rolling mill and method for the rolling of tubes

ABSTRACT

The disclosure of this invention relates to a cold pilger rolling mill for the rolling of tubes, having a reciprocating stand and grooved rolls mounted therein, and a device for advancing and/or turning the rolled material, and torque and mass compensation; the grooved rolls being in working contact with the rolled material at the outgoing travel and at the return travel, and releasing the rolled material for advance and/or turning before the outgoing travel and before the return travel.

United States Patent Gerretz et al.

COLD PILGER ROLLING MILL AND METHOD FOR THE ROLLING OF TUBES Inventors: Josef Gerretz, Viersen; Fritz Zeunert, Rheydt, both of Germany Assignee: Wean United, Inc., Pittsburgh, Pa.

Filed: May 22, 1974 Appl. N0.: 472,250

Foreign Application Priority Data June 7, 1973 Germany 2329526 US. Cl 72/208; 72/220 Int. Cl. B21B 21/00 Field of Search 72/208, 209, 214, 189,

References Cited UNITED STATES PATENTS Krause 72/214 X June 24, 1975 3,211,027 10/1965 Krause 72/208 3,584,489 6/1971 Petytavin ..72/1s9x 3,611,775 10/1971 Gabe] et al. 72/193 Primary Examiner-Milton S. Mehr Attorney, Agent, or Firm-Daniel Patch; Henry C. Westin [5 7 ABSTRACT The disclosure of this invention relates to a cold pilger rolling mill for the rolling of tubes, having a reciprocating stand and grooved rolls mounted therein, and a device for advancing and/or turning the rolled material, and torque and mass compensation; the grooved rolls being in working contact with the rolled material at the outgoing travel and at the return travel, and releasing the rolled material for advance and/or turning before the outgoing travel and before the return travel.

3 Claims, 5 Drawing Figures I sum PATENTEDJIJN 24 I975 fll COLD PILGER ROLLING MILL AND METHOD FOR THE ROLLING OF TUBES The invention relates to a cold pilger rolling mill, for example, as described in German Published Specification No. 1,602,036, as provided with torque and/or mass compensation. German Published Specification No. 1,602,036 indicates that the economic aspect of a cold pilger rolling mill can be used to the best possible extent if it is insured that the'rolls release the tube at the two ends of the path of movement of the said rolls, and that both an axial advancing movement and also a partial rotation of the tube are brought about at the two ends of the path of travel. This confirms a discovery explained in German Pat. No. 265,523 to the effect that after each travel it is possible to turn out in one case and back in the other so that each travel is a working travel.

In known grooved roll mills with jaw grooves, that is to say with grooved rolls whose working groove length amounts to only a relatively small portion of the periphery of the grooved roll, turning and advancing, which are referred to hereinafter as changing movements, do not present any difficulties since the remaining periphery of the grooved rolls is so large that it is possible to deduct from it a region for the changing movement at the run-in and also for the changing movement at the run-out.

When using grooved rolls with an extended working groove, for example, as proposed in U.S. Pat. No. 3,030,835, wherein the grooved rolls are in working contact over more than 270 considered over the circumference of the grooved rolls, no time remains for changing movements. The solution proposed in U.S. Pat. No. 3,030,835 was to make the grooved rolls carry out a working travel only at the outgoing travel; whereas at the return travel they are lifted away from the tube by suitable devices so that in relation to the crank drive there remains a period of time amounting to approximately 240 for carrying out the changing movement. But, in this way, the complete return travel is lost as a possible working travel.

Present-day cold pilger machines, which allow high working speeds, that is to say, high rates of travel per minute, because of the complete torque and mass compensation provided (German Pat. No. 962,062 and German Pat. No. 1,064,461 have, of course, as a result of the high working speeds to manage with continually decreasing absolute changing times. If output is to be increased by a changing movement both at the run-in and also at the run-out, the use of ring grooved rolls which are known per se in high-speed cold pilger roll ing mills is called in question since further changing time has to be provided between the outgoing travel and the return travel.

The invention has as its object to provide time for changing at the run-out in the case of more particularly high-speed cold pilger machines, without the rolling movement required for this purpose being at the expense of the working groove length, with the same diameter of grooved rolls, or resulting in an increase in the grooved roll diameter with the same working groove length. In the former case an increase in output which is possible by changing at the run-in and also at the run-out is canceled out again, at least, partly by the reduction in working groove length; whereas, in the second case, an increase in the grooved roll diameter would result in a substantial increase in the moved masses, since the grooved roll diameter ,has a decisive influence on the size and weight of the cold pilger machine. i

A solution of this problem can be achieved according to the invention in that the grooved rolls are ring grooved rolls known per sein cold pilger operations and that an arrangement is provided by,means of which the rotation angle of the ring grooved rolls .during an out and back travel is greater than 330. In a preferred embodiment the rotation angle of the ring grooved rolls is greater than 360. a

In this way the result is achieved that with the greatest possible. length of working groove in the ring grooved rolls sufficient time is available for a changing movement not only-at the run-in,'but also .at the runout. If the improved outputrequired by the measure provided by the present invention is to'concern not the length produced but the quality of the finished tube, the cold pilgerrolling mill according to the invention can also be used for material qualities which are difficult to roll or, for example, for the production of ball bearing tubes whereit is important to have narrow diameter and wall thickness tolerances, in such a manner that there is both turning and advancing of the roller material before the outgoing travel and only turning before the return'travel.

The invention is explaineddiagrammatically with reference to constructional examples in the accompanying drawings in which:

FIGS. 1a to 10 show three positions of the ring grooved'rolls during an outgoing travel,

FIG. 2 shows a side view of a cold pilger rolling mill,

and

FIG. 3 shows the roll stand as viewed in the direction of the rolling axis. i 1

FIGS. 1a, 1b and 1c show diagrammatically the progress of the rolling operation during an outgoing travel, and in FIG. 1a two ring grooved rolls are at the beginning of the outgoing travel. The ring grooved rolls 1 then move from the position shown in FIG. la in the direction towards the position shown in FIG. 1b and after a partial rotation through the distance a come into locking contact with the rolled material, a tube billet 3, in which a mandrel 2 is arranged in stationary manner. Working contact with the tube 3 is maintained over a partial angle b beyond the position shown in FIG. 1b. Then, the ring groove rolls 1 by suitable construction of the groove 6 in the said rolls release the tube 3 and move further by a further partial angle 0, until they come to a standstill as regards their rotational movement and also, of course, as regards their reciprocating movement. This standstill is achieved in the position shown in FIG. 10 and is marked on the ring grooved rolls 1 as A. T.

Starting from the position shown in FIG. 1 C, the ring grooved rolls 1 then move with rotation towards the left until the initial position shown in FIG. 1a is reached at the run-in dead center ET. From the run-in dead center E.T. to the run-out dead center A.T., the ring grooved rolls pass through an angle of rotation composed of the partial angles a, b and c in the illustrated preferred example more than 360. The partial angles a, b and 0 correspond in their development to the distances a, b and c, which together give the stand travel H.

FIGS. la, lb and 10 show that the ring grooved rolls 1 consist in known manner of a basic body 4 and rolling rings 5 mounted thereon, the groove 6 being formed in the rolling rings 5. 7 is the pitch circle diameter of the driving pinion 21 shown in diagrammatic manner in FIG. 3.

FIG. 2 shows a side view of all the important elements of a cold pilger rolling mill having a driving motor 9 which by way of a driving belt 10 drives a driving pulley 11 of a crank drive 8. The crank drive 8 has a crank radius r. Attached to the crank shaft are connecting rods 12 which connect the crank drive 8 with a reciprocating stand 16 and be means of a further rod 13 additional compensating weights 14. Further compensating weights 15 are connected with the crank drive 8 also. 17 indicates a turning and advancing arrangement.

An arrow 18 (FIG. 2) indicates the direction of advance of the rolled material.

In order to make it possible to achieve a rotation angle of the ring grooved rolls 1 which is greater than 360, the crank radius r is greater than the product d/Z' 11' wherein d is the diameter of the pitch circle 7 of the driving pinion 21 which is shown in diagrammatic manner in FIG. 3. FIG. 3 also shows the shafts of the ring grooved rolls, the stand bed 19 and stationary racks 22 with which the driving pinions 21 are in engagement.

In accordance with the provisions of the patent statutes, we have explained the principle and operation of our invention and have illustrated and described what we consider to represent the best embodiment thereof.

We claim:

1. Cold pilger rolling mill for the rolling of tubes, having a reciprocating stand and grooved rolls mounted therein, and a device for advancing and/or turning the rolled material, and having a torque and mass compensation arrangement, the grooved rolls being in working contact with the rolled material at the outgoing travel and at the return travel and releasing the rolled material for advancing and/or for turning before the outgoing travel and before the return travel, characterized in that the grooved rolls are ring grooved rolls in which a portion of their circumferences comprises cooperative tapered working groove portions, and said mill includes means for causing a rotation angle of said ring grooved rolls during each of an outgoing and return travel to be greater than 330, and wherein each angle of rotation of the ring grooved roll is smaller than the angle defined by said working groove portion plus twice the difference between this working groove portion and 360.

2. Cold pilger rolling mill for the rolling tubes having a reciprocating stand and grooved rolls mounted therein, and a device for advancing and/or turning the rolled material, and having a torque and mass compensation arrangement, the grooved rolls being in working contact with the rolled material at the outgoing travel and at the return travel and releasing the rolled material for advancing and/or for turning before the outgoing travel and before the return travel, characterized in that the grooved rolls are ring grooved rolls in which a portion of their circumferences comprises cooperative tapered working groove portions, and said mill includes means for causing the rotation angle of said ring grooved rolls during an outgoing and return travel to be greater than 300, and wherein the stand travel is greater than the pitch circle circumference of driving pinions of said means for causing rotation of said rolls which engages with stationary racks of a stand bed and means for connecting said driving pinions to shafts of said ring grooved rolls.

3. Cold pilger rolling mill according to claim 2 with a crank drive for the travel of the stand characterized in that the crank radius is greater than the product d/2 11' in which (d) is the pitch circle diameter of said driving pinions.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION PATENT NO. 1 3 890 821 DATED 1 June 24, 1975 INVENTOR(S) Josef Gerretz and Fritz Zeunert It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 3, line 13, "be" should read--by. Column 4, line 27, "300 should read "330 Signed and Scaled this A ties t:

RUTH cw MASON C. MARSHALL DANN Allzslr'ng Officer (ummissr'mwr nj'lalenls and Trademarks 

1. Cold pilger rolling mill for the rolling of tubes, having a reciprocating stand and grooved rolls mounted therein, and a device for advancing and/or turning the rolled material, and having a torque and mass compensation arrangement, the grooved rolls being in working contact with the rolled material at the outgoing travel and at the return travel and releasing the rolled material for advancing and/or for turning before the outgoing travel and before the return travel, characterized in that the grooved rolls are ring grooved rolls in which a portion of their circumferences comprises cooperative tapered working groove portions, and said mill includes means for causing a rotation angle of said ring grooved rolls during each of an outgoing and return travel to be greater than 330*, and wherein each angle of rotation of the ring grooved roll is smaller than the angle defined by said working groove portion plus twice the difference between this working groove portion and 360*.
 2. Cold pilger rolling mill for the rolling tubes having a reciprocating stand and grooved rolls mounted therein, and a device for advancing and/or turning the rolled material, and having a torque and mass compensation arrangement, the grooved rolls being in working contact with the rolled material at the outgoing travel and at the return travel and releasing the rolled material for advancing and/or for turning before the outgoing travel and before the return travel, characterized in that the grooved rolls are ring grooved rolls in which a portion of their circumferences comprises cooperative tapered working groove portions, and said mill includes means for causing the rotation angle of said ring grooved rolls during an outgoing and return travel to be greater than 300*, and wherein the stand travel is greater than the pitch circle circumference of driving pinions of said means for causing rotation of said rolls which engages with stationary racks of a stand bed and means for connecting said driving pinions to shafts of said ring grooved rolls.
 3. Cold pilger rolling mill according to claim 2 with a crank drive for the travel of the stand characterized in that the crank radius is greater than the product d/2 . pi in which (d) is the pitch circle diameter of said driving pinions. 